1. Technical Field
The disclosure relates to a gate driving circuit, and more particularly, to a gate driving circuit having high driving ability.
2. Description of the Prior Art
Liquid crystal displays (LCDs) have advantages of a thin profile, low power consumption, and low radiation, and are broadly adopted for application in media players, mobile phones, personal digital assistants (PDAs), computer displays, and flat screen televisions. The operation of a liquid crystal display is featured by modulating the voltage drop across opposite sides of a liquid crystal layer for twisting the angles of liquid crystal molecules in the liquid crystal layer so that the transmittance of the liquid crystal layer can be controlled for illustrating images with the aid of light source provided by a backlight module. In general, the liquid crystal display comprises plural pixel units, a source driving circuit, and a gate driving circuit. The source driving circuit is utilized for providing plural data signals to be written into the pixel units. The gate driving circuit comprises a plurality of shift register stages and functions to generate plural gate signals for controlling the operations of writing the data signals into the pixel units. That is, the gate driving circuit is a crucial device for providing a control of writing the data signals into the pixel units.
However, in the operation of a prior-art gate driving circuit, each gate signal provided by one corresponding shift register stage is unable to make a rapid shift from low level voltage to high level voltage in response to the level switching of one corresponding system clock, and therefore it is hard to enhance the charging rate of pixel units. In certain design of the prior-art gate driving circuit, the size of driving transistor in each shift register stage is enlarged for enhancing pixel charging rate, which results in significantly higher power consumption. Besides, if the gate driving circuit is integrated in a display panel having pixel array to bring the cost down, i.e. based on a gate-driver on array (GOA) architecture, the aforementioned shift register stages are sequentially arranged in a lengthy border area of the display panel for each shift register stage to be connected directly to one corresponding gate line, which means that the shift register stages are distantly separated from each other and the phenomenon of signal propagation decay becomes worse accordingly. Further, because the driving transistors of the GOA shift register stages are amorphous-Si thin film transistors (TFTs) having low driving ability, the driving ability of the gate driving circuit also becomes worse. Finally, since the driving ability of amorphous-Si thin film transistors drops significantly following a decrease of temperature, the turned-on driving current of a driving transistor without sufficiently high drain-source voltage drop is hard to achieve high enough for performing real-time display operation while starting an LCD under low working temperature, which may even lead to an occurrence of LCD starting failure.